A titanium-based oxide or lithium titanium-based oxide having a monoclinic β-type structure (hereinafter referred to as TiO2(B)) has recently been noted as an active material for a non-aqueous electrolyte battery. Spinel type lithium titanate (Li4Ti5O12) has been put into practical use. The number of lithium ions which can be inserted and released per unit chemical formula of the spinel type lithium titanate is three. Therefore, the number of lithium ions which can be inserted and released per titanium ion is ⅗, i.e., the theoretical maximum number is 0.6. In contrast, the maximum number of lithium ions which can be inserted and released per titanium ion is 1.0. TiO2(B) therefore has a theoretical capacity of approximately 335 mAh/g which is an excellent property.
However, a practical electrode capacity of TiO2(B) is approximately 170 to 200 mAh/g, which is remarkably deteriorated as compared with the theoretical capacity. This is considered to result from the fact that although a number of sites of Li hosts exist in a crystal structure of TiO2(B), a small number of mobile Li ions are effective since Li ions in a solid have small diffusivity.